Eighteen days before Iowa voters cast the first ballots of the presidential race in their caucuses, six Republican candidates launched steady attacks on front-runner Donald Trump, yet appeared to gain little ground. 

The attempts to bruise the billionaire, who leads national polls of GOP voters and also most state surveys, ranged from his proposal to slap a tariff on Chinese goods to his call to ban Muslims temporarily from entering the U.S. to his attacks on one of his chief rival's eligibility to run for the nation's highest office. 

During a lengthy and heated back-and-forth at Thursday's Republican presidential debate in North Charleston, South Carolina, Donald Trump admitted that he's bringing up U.S. Senator Ted Cruz's Canadian birthplace "because now he’s doing a little bit better" in the polls, and insisted that Cruz receive a judgment from the courts because it would be bad for Republicans to have the issue hanging over their presidential nominee.

The Texas senator chuckled when asked to respond to Trump's taunts that he may be ineligible to be president of the U.S. Then he swatted them away deftly. Trump, on the other end of the exchange, faced many boos from the crowd. 

"I'm glad we're focusing on the important topics this evening," said Cruz, who was born in Canada to an American mother and has been a U.S. citizen since birth. He noted that Trump had last year he's a natural born citizen.

"I don't care. I think I'm gonna win fair and square. I don't have to win this way," Trump said.

Trump also ruled out suing Cruz himself. "I'm not bringing a suit, I promise," he said. "But the Democrats are going to bring a lawsuit." In fact, one of Cruz's constituents did on Thursday.

China Tariff

At several points in the debate, Trump's rivals suggested that the billionaire businessman doesn't understand the nuances of governing and diplomacy. While Trump said that The New York Times was "wrong" in reporting he'd favor a 45 percent tariff on Chinese goods, he later acknowledged "I'm totally open to a tariff," accusing China of engaging in unfair trade. "We don't have to continue to lose $505 billion for the privileges of dealing with China," Trump said.

Former Florida Governor Jeb Bush—whose father, former President George H.W. Bush, served as an envoy to China—and U.S. Senator Marco Rubio of Florida differed. "We are all frustrated with what China is doing but we need to be very careful with tariffs. China doesn't pay the tariff. The buyer pays the tariff," Rubio said.

The sparring over China provided a rare on-stage triumph for Bush in his long-running feud with Trump, who was booed by the crowd when he said the country does not need "a weak leader" on trade like Bush. 

Ohio Governor John Kasich, citing his blue collar roots in the steel towns of Western Pennsylvania, expressed more sympathy with Trump's point of view, saying that it takes trade courts years to settle cases when countries send cut-rate goods into the U.S., undermining jobs. "What do we tell the workers?" he said. "They're Americans and they carry the load."

Muslim Travel Ban

Later in the debate, Trump won applause from the audience for answering with a terse "No" when asked if he would reconsider his controversial proposal to ban Muslims from traveling into the U.S. "We have to stop with the political correctness" he said.

But some of  his rivals on stage said the businessman's proposal threatened to alienate the very Arab allies the U.S. needs in its war on the Islamic State. The attack was led by Bush, who called Trump's statement "unhinged."

"Are we going to ban Muslims from India, from Indonesia, from other countries we need to build a partnership against ISIS?" asked Bush. Kasich agreed. "We need the Saudis, Egyptians, the Gulf States and Jordan," he said, naming other U.S. allies in the region.

Other candidates on the stage, while not endorsing Trump's proposed travel ban, avoided criticizing it. Rubio said Trump is reflecting anger over Obama's policies. "The president has consistently underestimated ISIS," he said, adding: "If we do not know who you are and we do not know why you are coming when I am president you are not getting into the United States of America."

New York Values

Heading into the debate, the spotlight was on the surging insurgents, Trump and Cruz, who are locked in a dead heat for first place the Feb. 1 caucuses and who have recently dropped the elaborate truce they maintained for most of the campaign in favor of all-out attacks on each other.

Trump is accusing Cruz, born to an American mother and a Cuban father north of the border, of being a Canadian. Cruz has labelled Trump something considered even more alien in many parts of the country: a New Yorker

Asked what he meant by accusing Trump of having "New York values," Cruz said "Not a lot of conservatives come out of Manhattan. I'm just saying."

"Conservatives do come out of Manhattan," said Trump shot back, invoking the city's mettle in the face of one of its greatest tragedies. A the terror attacks that brought down the World Trade Center, "everybody loved New York and loved New Yorkers," Trump recalled, adding: 

"I have to tell you, that was a very insulting statement that Ted made."

The Undercard

Carly Fiorina may be struggling in the polls but she was having no problems on the debate stage at an earlier face-off for lower-polling contenders. The former Hewlett Packard CEO kicked off the Republican presidential candidates' sixth debate night with biting attacks at both political parties' front-runners.

"Unlike another woman in this race, I actually love spending time with my husband," Fiorina said, eliciting whoops and cheers with her clear reference to the Clintons. 

Fiorina quickly turned her sights on Trump, mocking him for "raking in billions" to buy politicians and scoffing at his "bromance with Vladimir Putin," the president of Russia, with whom Trump has traded compliments. "Iran and Russia are our enemy," Fiorina continued.

Recognizing 50 audience members—including two of his sons—currently attending the Citadel, a Charleston-based military academy, former U.S. Senator Rick Santorum charged the Obama administration with offering "courtesies to Iran" after it recently detained and released U.S. sailors. "I will have your back," Santorum told the cadets.

Former Arkansas Governor Mike Huckabee expressed doubts about keeping troops in Afghanistan, which he described as "the land of the Flintstones," arguing that "the role of the U.S. military is not to build schools ... it's to kill and destroy the enemy." 

Also invited but absent was U.S. Senator Rand Paul of Kentucky, a presidential candidate who decided to skip the debate because he didn't qualify for the main stage. The Kentucky senator held a town hall, made other TV appearances and kept up an ironic commentary on the proceedings via Twitter.

 

 

Twitter: Dr. Rand Paul on Twitter